Instant stop and start blasting device



1956 w. H. MEAD ETAL INSTANT STOP AND START BLASTING DEVICE 2Sheets-Sheet 1 Filed April 1, 1954 T m mnwfl MMBJ E wi /m N A n mwz mHAM T M 4 A 4 um. L MMMU v! a .1 6

INSTANT STOP AND START BLASTING DEVICE William H. Mead, Oakland, ArthurA. Zambruno, San

Mateo, and Alexander L. Jett, Menlo Park, Calif., assignors, by mesneassignments, to William H. Mead, Oakland, Calif.

Application April 1, 1954, Serial No. 420,254 18 Claims. c1. 51-8 Thisinvention relates to a novel method and apparatus for cleaning ortreating surfaces and, broadly, has to do with the art of cleaning ortreating surfaces in which an abrasive material or substance is impingedagainst the surface.

The invention provides for the first time a portable, lightweight,efiicient blast cleaning device useful in removing paint, rust, scale orany other deposit from off a surface being cleaned without scatteringthe removed scale and the spent abrasive over the whole adjacent area.It provides for the first time such a device in which there are nomoving parts, thus rendering it fool-proof and easy to maintain. Itprovides for the first time such a device which can be used in an engineroom or other like confined area without requiring adjacent equipment tobe covered to protect it from flying abrasive and scale. It provides forthe first time such a device in which the flow of abrasive to the blastgun stops immediately upon the closing of the control valve and theabrasive in the supply line is pulled back into the abrasive storagechamber leaving the supply line clear for an immediate start. Otherobjects and advantages in addition to the above will become apparent asthe description of a preferred embodiment of the invention is now given.Also with this description before him the man skilled in this art willbe able to devise modifications of the apparatus, because the. inventionand its principle is capable of being embodied in more than the one formdescribed in compliance with the Statute. In the drawings:

Fig. 1 is a view in perspective of a somplete apparatus constructedaccording to the present invention;

Fig. 2 is a diagrammatic representation of the device of Fig. 1,explaining its mode of operation;

Fig. 3 is a view in vertical cross-section through a blast gun of thetype preferred for use in the device of Figs. 1 and 2; I

Fig. 4 is a similar view of a separator and reclaimer tank of the typepreferred for use in the device of Figs.

1 and 2, taken along the line 44 of Fig. 5, and showing, also, thebypass abrasive control conduit;

Fig. 5 is a top plan view of Fig. 4; and

Fig. 6 is an enlarged detail view of the abrasive outlet from the tankof Fig. 4,'showing the position of the treating material adjacent theoutlet when the device is not in operation.

Broadly, the present invention includes a surface-treating head or gun A(see Fig. 2) which is supplied, through a supply line B, with abrasivefrom the abrasive storage bin C. When blasting, the abrasive is pulledinto the nozzle in the gun A and is impelled at the surface beingtreated by the air jet assembly D. The lower end of the gun A isconnected to the suction pick-up line B which has maintained therein areduced pressure, the net effect of which is to pick up and carry awaythe spent abrasive and the scale loosened from the work surface. Anotherefifect of the reduced pressure in the lower end of the gun A is to pullin enough air from the outside through its pervious maze so that none ofthe abrasive or scale United States Patent can get out from under thegun. Completing this embodiment of the invention is a bypass abrasivecontrol line F, which, in conjunction with the gun control valve G inthe air-supply line, and the suction in the abrasive .pickup line Bpermits a very desirable emptying of the abrasive supply line B, therebygiving instantaneous control over the stopping and starting of theblasting action within the head A. While we have shown a particularlyefiicient separator-reclaimer R,.cyclone S and vacuum ejector pump P,these are parts which can be varied and replaced by other devices toperform like functions.

This instanstaneous control over the abrasive flow is achieved byconnecting suction lines B and F to a single outlet from the abrasivestorage bin C. When there is suction in the line B produced by the jetassembly D in the plasting gun A it is of greater intensity than thesuction in the line F created by the ejector pump P so the abrasiveflows through the abrasive supply line B to the gun A. The instant thegun control valve G is closed, suction being created by the jet assemblyD stops and the abrasive in the supply line B stops moving toward thegun A. Then the suction in the bypass abrasive control line F takes overand draws all the abrasive remaining in the supply line B into the lineF and dumps it into the reclaimer R. The. suction in the line F is ableto do this because the end 'of line B in the gun A is open toatmospheric pressure. The net result is that so long as the suction ismaintained in the line F and the valve G is closed, abrasive will keepcycling through the bypass abrasive controlrline F, through thereclaimer R, then by gravity into the abrasive storage bin C into the Tand into the line F. The instant the valve G is opened, the suctioncreated in the line B will draw the abrasive from the bin C through theempty hose B into the gun A. The spent abrasive then returns with theloosened scale to the reclaimer R through the hose E.

Referring to the drawings in detail, 10 indicates the work surface beingtreated by an abrasive surfacetreating "material 11, in a treating zone12. This work surface may be wood, glass, metal, cement or a synthetic,and may be covered with paint, rust, scale, or other material 9 which itis desired to remove. The surfacetreating material 11 may be an abrasiveor a covering material, depending upon the treatment it is desired togive the surface 10. For purposes of illustration, an abrasive treatmentwill be dealth with, and this is not intended to mean any relinquishmentof the scope 'of interpretation of the invention.

The illustrative apparatus shown in Fig. 1 is movably mounted on alightweight wheeled frame 13 to permit it to be moved about easily whenbeing used. It is coupled to a source 14 of compressed air by the hose17. Any type of air-velocity means or pressure accumulator 14, such as amotor-driven conventional air compressor, may be used. Preferably, aconstant pressure outlet valve 15 is interposed in the line to regulatethe pressure and volume of air metered to the surface-treating apparatusfrom the source 14.

Compressed air is piped from the source 14 through the inlet conduit 17to a main hand-operated valve V on the unit. Upon opening the valve V,the air passes into an aridifier or moisture trap 18 which separates themoisture in the air stream and permits the moisture to be blown downthrough the valve 19. From the aridifier the air passes through theconduit 20 and is divided into branch conduits 21 and 22. The conduit 21conducts the air to an ejector pump P which creates all the suctionneeded for the spent abrasive and scale pick-up line B and for thebypass abrasive control line F. The conduit 22 conducts air to the jetassembly D where the air :flow performs the dual function (a)"of suckingthe abrasive material 11 from the T where it has fallen by gravity fromthe storage bin C, and through the abrasive supply line B into the jetassembly D on the gun A; and (b) of impelling the abrasive at the worksurface 10.

The main suction system The suction circuit initiated by the air flowinginto branch conduit 21 will be considered first. As indicated in Fig. 2,the compressed air passes from the conduit 21 into the ejector pump Pwhere it is jetted through an annulus 23 at very high velocity into thethroat of a mixing tube. By adding the ditfuser 24 the maximum energy istaken from the air flow. By properly proportioning the annular throat ofthe ejector pump, the size of the diffuser and the volume and velocityof the entering air, the ejector pump can be made to entrain the airfrom the conduit 25 and produce the desired degree of vacuum. The vacuumor subatmospheric pressure, thus created supplies the suction in thespent abrasive and scale pick-up line E leading from the blasting gunhead A, and acts to pick up all the loosened scale and the spentabrasive as soon as it has impinged against the work surface in thetreating zone 12. The pump P and associated conduits thus act as asource of suction connected to the reclaimer R.

The suction created by the ejector pump P, in addition to the foregoing,also supplies the air flow needed in the separator and reclaimer R, inthe cyclone S, and in the bypass abrasive control line F making the sameair do double duty, that of conveying and air washing the reusableabrasive.

The separator and reclaimer R It is a feature of the preferredembodiment illustrated that all the spent abrasive 11 removed from thezone 12 be reused many times which requires that it be separated fromthe entrained dirt and debris after each trip to the gun A. To achievethis result, a suitable separator-andreclaimer tank R is needed. Itshould be noted, though, that the invention may be employed without areclaimer positioned between the suction line E and the ejector pump P.The form of separator and reclaimer shown in Fig. 4 has an upper chamberwith a novel system of bafiles and passageways which are particularlyeffective in separating the abrasive from the entrained dust and scale.The latter then pass on to the cyclone S where the scale and most of thedust is captured in the receptable 29 below the cyclone S. If there isan especially large amount of dust being lifted off the work surface,that part which is not caught in the cyclone will be caught in the dustbag 51. For most work the dust bag is not needed.

In operation, the tank R acts to separate and reclaim the abrasive 11from the fines and debris 26 removed from the treating zone 12 by thesuction pick-up line E, so thatthe abrasive may be collected for reuseinthe lower reservoir portion 30 of the tank. As the mixture of scaleand abrasive enters the tank R, it is directed by the tangential inlet'32 in a circular path within the battle 31. Centrifugal forcegenenrated by this circular motion accomplishes an initial separation ofthe abrasive and scale particles from the air stream so that theabrasive and scale will be spread out over the relatively large area ofa conical slide 33. An intermediate oppositely directed baffie 34restricts the downward flow of the air stream and also acts to deflectthe abrasive and scale particles which are moving on or close to thewall 31 onto the upper surface of the stratifying slide 33. As theabrasive and scale particles move down the conical slide 33, theincreasing surface area presented permits the particles to spread outand for each particle to come into contact with the slide rather than toremain piled on top of another particle. Consequently, when the solidparticles cascade over the lower perimeter of the cone 33, as a filmabout one layer thick, the relatively heavy individual particles ofabrasive and the relatively light more circuits around the chamber 31,meanwhile flows up the channel 35 formed by the annular flange 36surrounding the discharge pipe 37 by reason of the larger area. It thenmoves down the annular channel 38 formed between the outer tank wall 39and baifle 31. The air takes this path because of the restriction formedby the relatively narrow gap 39a between the cone 33 and the deflectingbaflie 34 which only lets a small amount of the air through this gap.Thus the bulk of the air sweeps down the channel 38 and through anannular opening 40 between the cone 33 and the lower adjustable cone 41.As a result, the cascading abrasive and fine particles are subjected toa cross-current of air which sweeps the fines, scale and dust particlesinto the space between the cones 33 and 41 into the discharge stack 37and over into the cyclone S. The heavier abrasive particles fall bygravity into the abrasive storage bin C through the gap at the lowerperiphery of the cone 41. Any oversize particles that escaped removalabove are caught on the sloping screen 42. The screen '42 also serves toremove any oversize particles in the abrasive when it is first loadedinto the bin C through an opening 104 provided for that purpose. A door103 enables any screened coarse material to be removed periodically. Acurved baffle or floor 43 is provided to guide the abrasive toward theoutlet 44 leading to the abrasive supply and control lines B and F.

The effectiveness of the separator and reclaimer R is dependent onhaving the proper velocity of the crosscurrent air sweeping into the gapbetween the cones 33 and 41. The necessary range of velocities will varywith the types of abrasive material used. This velocity must be greatenough to carry the individual dust or scale particles out from amongthe abrasive particles so they will be swept up between the cone 41 andcone 33 and then out the pipe 37. The cone 41 has less slope than thecone 33 (see Fig. 4) thereby providing a space be tween them whichincreases in area in the upward direction. Thus, should a reusableabrasive particle be unswept into the area, the progressive enlargementof the area will slow the air flow and will allow the particle to settleand return to the opening 40 and to fall down into the storage bin 30.In general, the air velocity of this cross-current must not be greatenough to pick up the abrasive particles themselves, as they should fallin the first instance into the abrasive storage hopper 30. To adjust theair velocity the lower cone 41 is raised or lowered to vary the width ofthe entry gap 40 between the two cones 33, 41. Thus, if a relativelyheavy abrasive is used, such as steel grit having a mass of aproximately265 lbs/cu. ft., the cone 41 would be raised to decrease the gap andthereby achieve a relatively high sweep velocity. With a lighterabrasive, such as sand (approximately lbs./cu. ft.), the cone 41 would.

be lowered, thereby widening the gap and lowering the velocity of theair so it would not sweep the sand particles up the conduit 37 alongwith the scale. A suitable adjusting means for this purpose isillustrated in Fig. 4, which shows the cone 41 adjustably mounted on avertical shaft 45 by a sleeve 46 and adjusting screw 47. Of course, anyother convenient means could be used. For certain abrasives, such asground walnut shells (35 lbs/cu. ft.), it may be desirable to remove thecone completely to further reduce the sweep velocity.

Separating the air from the dust and scale After leaving the separatorand recl'aimer R,the debris and dust-laden air is sucked through conduit48 into a conventional cyclone separator SLwhereathe bulleofl any;

contaminant-s remainingin the :air are removed'by centrif? ugal for'ce'.The solid particles are thrown againstthewall.

50' and conduit 25" into the ejector pump P which constitutes the sourceof the suction circuit. The suction circuit-is completed when the air isexhausted from the pump P through the diifuser 24. Preferably, a-dustbag 51surrounds the diffuser so that any remaining fine dust willibe.

removed from the airbefore it is exhausted to the atmosphere.-

The blast gun suction system Next tobe considered is-the. air blastcircuit supplied by the branchconduit 2'2 which leads-into thebl'astinggun A. As shown in Fig. 2, the-air passes fromthe line' 22;throughrnanual c'ontrolvalveG, into the jet'assembly D, where it servesthe dual-functional) of sucking the |abrasive-11 through the abrasivesupply line B from the abrasive reservoir 30 and (b) of impellingjtheabrasive at the? work surface enclosed within the blastinggun A1 Broadlythisfunction is achieved by surroundingthe jet- 60 leading'from theabrasive supply lineB with a mixing. Air passing through the annularorifice 6'2"- tube 61. formed between'the two members 60 and 61 willpull'air from the abrasive supply line B. The motion-of the airwil-l'carry the abrasive 11 through theb'ore of the-jet nozzel 60depositing itin frontof the blast of air emerging up the-abrasive and:

from the orifice 62 which blast picks impels-it against'the work surfaceWithin theblasting gun orhead'A, it is important that two impingingaircurrents are provided so that the blast ing and pick-up elfect,described in the Mead U. S. Re-' issueP-atent No. 23,186 will bepresent. One of these currents is the air blast from line 22 which'sucksthe abrasive through the jet and throws it against the work surface :10.The other current is the flow induced in the suction pick-up line Bwhich causes an 'air'sweep into-the head A through an air-.perviousmazeor impeding-means 63-conneotedto the casing SI-andicontacting thework surface 10. These two currents meet just inside the mazeorxair-pervious deflector means and form :a pick-up force I Whichliftsthe spent abrasive and the scale upwardly and out through the pick-upline E. In this respect the operation of the blast gun A is identical'witht-hatdescribed in the above patent, wherein the net effect is acompletescavenging of the @work area within the treating zone of allscale and spent-abrasive without any 'ofthe abrasive or scalegettingthrough' the maze-63where it might in' jure delicate machines-andother finished surfaces.

The I blasting gun A An'illus-trative apparatus fortheblastinggunand-head A is presented in-Fig. 3, which shows an inner casing or shell72 which serves to direct'onto'the 'surfiace 10 the abrasive 1 1 issuingfrom the jetassembly D. The mouth 74 of thecasing 72 confines the workarea 10 to the treat iug zone 12. A-second or out-creasing 75'surroundsthe inner casing 72 adjacent the mouth 74 of the latter. How far up theoutside of the casing 72-the-outer casing extends is. a matter ofchoice, the critcrionbeing a size and shape that will giveasustained'velocity to the'air flowindicated' by the arrows 76* so thatthe air currentwill have a high weight-sustaining or carryingcharacteristic. This charac-- The-maze '63; batfie and body 81" may bethought 'of as constituting,- togetherwith other associated parts, ahood that encloses a portion of the surface aroundthe area being...

treated Adjustments for difierent quantities of abrasives One feature ofthe apparatus illustrated inFi g. 3 is-the provision for an adjustingmeans within the jet assembly.

D so that any desired amount of abrasive may be caused to flow in :agiven time intervalto'fit the requirements of dilferent abradingoperations. Thisadjustment may'be achieved by a threaded connection 83between the-separate structures-of the jet nozzle 60:=and=the-mixingtube 61. By manipulating the threaded connection 83,- the annulargap 62between the :jetand the mixing-tube may be widenedor narrowed. Theextentof the" adjustment may be gauged by the numberof shims-82interspersed metering orifice 851's provided "in the-feed outle-t44, so3 that .the flow of abrasive into the abrasive supply-line B wil-l beregulated'to cause the amount of abrasive 1 02;

droppinginto the pipe tee 90 beneath the pipe 44'- to equal what theflow of air created by the jet D cancarry Thus, the relationship betweenth'eannular orifice 62and the metering insert 8 5 is such that theorifice 85 will be increased in size, as the gap-in the orifice 62is-increased. The right size of orifice 85 will allow only theamount ofabrasive to fall into the-tee 90, as can be airborne by the flow of aircreated-by. the jet D. The only-time the abrasive 102 lies in the pipe'is when the-valve V closed.

Abrasive control mechanism Early in this specification appeared anexplanation of the broad structure by which instantaneous control overthe abrasive is obtained in a very simple and unique manner. Thisstructure is shown in detail in Figs. 2 and'4, where the by-passabrasive control line-F is connected to" one end of'a T fitting .90secured to the abrasive storage bin outlet 44, and at its other end itis connectedinto the suction pick-up l-ine E at some. convenient point,preferably just before the line B enters the reclairnertank R. The otherend of the T-fitting 90 is connected to the abrasive supply line Bleading into the blasting gun and: head A. In operation, the function ofthe bypass control line F is closely tied'in with the operation ofthe'cont-rol valve G which supplies air to the jet assembly D. When thevalve G is open, the air passing through the orifice gap 62'creates aflow of air in the supply line B'which picks up the abrasive in theT-fitting 90 below theorifice 85 and carries the abrasive from theabrasive storage bin C through the jet 60 into the blastinghead-A'.

In normal operation, the suction at the abrasive supplyline B side ofthe T-fitting 90 is proportioned to be somewhat greater than that in thebypass line F so that when the valve G is open the flow of air andabrasive-is to the blasting gun A. During. this stage of the operation,-termed for convenience the blasting stage, the jet assembly D assumescomplete control over the through the blasting head A and back to theseparatorrec'laimer R through the pickup, line E. The path ofthisblasting cycle is indicated by the arrows in Fig; 2. It is apparentthat any abrasive particles movingin-thiscycle in the supply line B willdevelop considerable kinetic energy as they are sucked into the blastingjet- 60.

The importance of the bypass control line Flies in its. instant abilityto overcome the kinetic energy of the flow:

line B back away from the nozzle 60'." Another important.

abrasive cycle valve G. Thus no complicated electrical or other remotecontrols and no extra valves are needed.

Operation The over-all operational cycle of the abrading apparatusdisclosed is as follows:

A suitably-sized orifice 85 is inserted in the feed outlet 44 and theorifice gap 62 in jet assembly D is adjusted for the particular quantityof abrasive 11 that is to be fed in the abrading operation. Also thecone 41 is set to provide the proper gap 40 in the reclaimer R. A chargeof the desired abrasive is then placed in the reservoir 30 through thefilling spout 104 above the screen 42. At this stage the abrasive seeksits level through the screen 42, outlet 44, and orifice 85 and formsinto a mound in the T-fitting 90, with its angle of repose generally asshown in Fig. 6. The device is then ready to be rolled up to the workarea on its wheeled frame B, where a connection 16 may be provided to acompressed air source 14. The blasting gun and head A is then placed onthe work surface 10 preparatory to blasting.

Blasting is initiated by first opening the main valve V which starts theejector pump P in the suction circuit. At this stage air begins to flowinto the reclaimer R, and the cyclone S (a) through the pickup line B,and (b) through the abrasive supply line B, the mixing tube 61, the cone72, the maze 63, and the bypass line F. Through the pickup line B thesuction circuit applies an operating vacuum on the treating head A,while the suction in the bypass line F scavenges the build-up ofabrasive material in the T-fitting 9t) and also acts to clean out thefeed outlet 44 and orifice 85 prior to actual blasting operations. Theabrasive continues to cycle from the outlet 44 through the line F intothe reclaimer R. To start actual blasting the control valve G is openedto admit the air blast to the chamber in the jet assembly D, so that itmay pass through the orifice gap 62, causing the blasting jet 60 toproduce a suction in the line B. Suction in the line B causes theabrasive falling through the orifice 85 into the T-fitting 90 to flowinto the abrasive supply line B, into the blasting jet 60, and onto thework surface. There the abrasive elfects a loosening of whatever scaleor coating 9 may be covering the surface 10. After the abrasive material11 impinges on the work in the confined area, this material 11immediately comes under the influence of the air stream flowing inwardlythrough the maze 63 in the blast gun A, with the result that the two airstreams impinge and lift off the surface 10 the spent abrasive and theloosened scale or coating. These are conveyed away out of the operatinghead A through the flexible pickup line B and into the separator R. Theblasting gun A is moved over the working surface 10 as fast as the scaleis removed. In the drawings it has already moved over the surface lyingto the right of the treating zone 12 and is being moved to the 'left toclear that surface of the scale 9.

In the reclaimer and separator R the scale and dust is separated 'fromthe abrasive and the latter drops into the abrasive storage bin 30. Thedust and scale go on to the cyclone S where most of the scale and dustis removed from the air. As a final step in very dusty work the air ispassed through a dust bag 51 before being exhausted. The blastingoperation can go on continuously as the abrasive is used over and overagain.

When the operator wishes to lift the blasting gun A off the surface 10for any reason he closes the valve G which stops the flow of air to thejet orifice 62. This discontinues the suction in the abrasive supplyline B in the direction of the arrow 100 and the suction in the bypassabrasive control 'line F takes effect reversing the flow of air in theabrasive supply line B and in the bypass line F so the abrasive in theline B is pulled back away from the nozzle 60 and is carried through theline F into the reclaimer R. As soon as the line B is cleared, moreabrasive is picked up below the orifice and there is a continuouscycling of abrasive in the direction of the arrows 101 (Fig. 4) untileither (a) the ejector pump P is shut down or (b) the valve G is openedand blasting is resumed.

By combining the maze 63 and the blasting gun A with the conduits B, Eand F, the maze not only performs the functions set forth in ReissuePatent No. 23,186, but it performs in this new combination theadditional function of providing an inlet so that air may flow freely inthe reverse direction to those denoted by the arrows in conduit Bwhenever the gun valve G is closed.

As noted earlier, the device illustrated is a preferred form and thisdescription is not intended as a disclaimer of other forms in which thisinvention may be embodied. Also attention is called to the fact that inlieu of the ejector pump P any other suitable source of vacuum may besubstituted. Also, where abrasive is plentiful and need not be reusedthe pickup line B would go directly to the vacuum source, omitting thereclaimer R and the cyclone S. The bin C would be kept filled withabrasive and the instant the blast gun A was turned off the bypass lineF would clear the abrasive supply line B. If the gun A were to remaininactive for any length of time, a suitable valve at the bottom of thebin C could be provided to avoid wasting the abrasive.

From the foregoing it will be apparent that this method and apparatusmake possible the use of a small, portable treating device that isideally suited for use around delicate machinery, as in automobilerepair shops, or on shipboard, or in closed rooms, or in any area orapplication where complete and instantaneous control over both thetreating action and the treating material is required. Thus, with thepresent invention not only is the area of treatment controlled, sincethere is no escape of the treating material from the treating head, butalso the time of treatment maybe carefully controlled, since the flow ofabrasive to the work area can be instantaneously started and stoppedwithout any time lag.

To those skilled in the art to which this invention relates, manychanges in construction and widely difiering embodiments andapplications of the invention will suggest themselves without departingfrom the spirit and scope of the invention. The disclosures and thedescription herein are purely illustrative and are not intended to be inany sense limiting.

We claim:

1. A surface treating device comprising a supply source for the treatingmaterial; a reclaimer separator having an inlet, an air outlet, and aconnection to said supply source and adapted to deposit cleaned treatingmaterial in the latter; a blasting gun for directing said material atsaid surface; control means for activating and inactivating said gun; ahood enclosing said gun, said hood having an open end with a perviousmaze bordering said end to enclose a portion of said surface around thearea being treated; a source of suction connected to said air outletfrom said reclaimer; a first conduit connecting said hood to the inleton said reclaimer; a second conduit connecting said supply to source tosaid gun; means for producing simultaneously a suction in said secondconduit and an impelling force in said blasting gun whereby treatingmaterial will be caused to flow in said second conduit to said gun; athird conduit connecting said second conduit and said supply source tothe inlet end of said reclaimer and therethrough to said source ofsuction; whereby upon activation of said gun, the suction in said secondconduit will move said treating material to said gun as needed, and thesuction in said first conduit will remove from the surface area enclosedby the hood the spent treating material and through said second conduitthereby moving outof' said second" conduit into said" third conduit andinto. said reclaimer'" any treating material in, said second conduit;and so'long as the source of'suction is connected'to said treclaimer andsaid gun is, inactivated; said treating material'will be cycled throughsaid third-conduit, said reclaimer'and said supply source.

2. A surface treating device comprising a supply source for thetreatingmaterial; a blasting gunfor directing said material atsaid-surface; control means for activatingfand inactivating said gun;,ahood enclosing said gun, said hood having an open end'with apervious-maze bordering ,said endvto enclose arportion of said surfacearound the area beingtreated; a source of suction; a firstconduitconnecting saidsource of suction to said hood; a second conduitconnecting said supply source to said gun; impelling means for producingsimultaneously av suctionin said second-conduit and an impellingvforceinsaid blasting gun whereby treatingsm aterial will be caused to flow insaid conduittosaid gun; a thirdiconduitwconnecting, said second.conduitand said supply source to saidsource of suction;.whereby uponactivation of said.

impellin-gmeans, the.suction in said second conduitwill move saidtreating material to said:impelling means as needed,.anduponhinactivationofsaidgun, the suction in said thirdiconduitwill becomeeffective inv said. second conduit to move. any treatingmaterial'therein'into' said third conduit and away. from saidgun.

3. A surface treating device comprising a-supplysource for the treatingmaterial; anblasting gun for directing; said. material. at-said surface;a hood enclosing said gun and .having, an open end to enclose I aportion of said' surface; a source ofsuction; a conduit connecting saidsource. of. suetionto said hood; a-secondconduit con necting.said.supply source to said blasting gun; means. for producingsimultaneously a suction. inisaid second conduit and an impelling forcein said blasting gun whereby treating material will be caused to flow insaid conduit suction-removed'abrasive having air: compressor"m'eans forimpelling said abrasive at-thesurface being treated,

vacuum means forconveying the: spentiabrasive away from-said surface;and bypass control'means for elim inating time lag in the operation ofthe device; thecombination of a-treating head'spaced slightly above andhaving an air-pervious maze" adapted to cover-over aportion of thesurface being treated, said treatinglhead' having anopen. end, .a; jet 3means therein withits"- open end pointed towardthe opentend ofsaidheadandwith' its other end connected'tossaid air compressor andto'asupply line in communication with a source of abrasive, a vacuumconduitfrom'said head to said vacuum means,

albypass control line leading from-said vacuum' conduit" to both saidsupply line and said-sourceof abrasive; and

a control valve interrupting'the flowof abrasive from said aircompressor'to said jetmeans, wherebyorr closing said valve during normaloperation of the-device; a

flow ofabrasive'throughsaid supply line into said treating head will'beinstantaneously"redirected throughsaid bypass'vcontrol line.

5. Ina device-for treating a surface with an'air-blasted;

suction-removedabrasive. having high air velocity means forimpellingisaid. abrasive. at .the surface being treated," and forproducing. reduced. pressure: for conveying the spent abrasive awayfromsaid surface, and havinga'by pass controlmea'ns "for-eliminatingtime lag in the operation ofthe device; the-combination of a treatingh'e'ad spaced slightly above and having anair-pervi'ous maze adapted tocover over a" portion of the surface being.

treated, said treating head having an open end, a jetmeans'thereinwith'its open end pointed toward'the openend" of said headfor impelling said abrasive at said surface, and adapted to be energizedby'said air'velocity,

means; a first conduit forming a supply line between a source ofabrasive and" said jet means, said jet means creating a reduced pressurein said supply line to induce a flow of abrasive therein to said jetmeans, a secondconduit connecting saidhead to said air velocity meansfor conveying the spent abrasive away from said surrupting. the flow ofair from said air velocity means tosaidjet means, whereby on closingsaidvalve to end the blasting operation said jet means is de-energizedcausing the pressure at the outlet end of said second conduit to becomelowerthanthe pressure at-the outlet end of said first: conduit so thatthe flow of abrasive through said first conduit is reversed and flowsthrough said third conduit.

6. An apparatus for treating a surface with an airblasted,suction-removed abrasive and for substantially eliminating time lag in'theoperation of the apparatus,- which com-prises a treating head,including deflecting and impeding meansltoprevent loose material fromflying about and'to confine the areaof treatment, a source of abrasive,a supply line from said abrasive source to the head, a suction circuit,an exhaust connection between said suction circuit and said head,separating and reclaiming means for said abrasive interposed insaidsuction' cir-' cuit, a bypass suction lineleading from said suctioncirwit to aconnection with both-said supply line and-said abrasivesource,- air*jet means in said treating head connectedto saidabrasive'supply line, and valve means regulating-the flow of-air tosaid-jet means, whereby during a blastingstage of operation said jetmeans creates sufficient pressure to such abrasiveinto a jet blastingvaction insaid head from which bothspent abrasive and loosened debris'may be removedfrom the surface by the suction circuit and the abrasivereturned to saidabrasivesource through said separating and reclaimingmeans, but on closing said valve said bypass line' redirects the flow ofabrasive away from. the treating head into an abrasive recycling. stageof operation through said separatingandreclaimingmeans, therebypermitting instantaneous stopping of the abrading action upon valveclosure.

7. The device of claim 6 in which said source of abrasive comprises'ahopper inthe' bottom of said separating and reclaiming means, a feedoutlet from'said hopper, and

a T-fittinglconnecting said outlet"v to said bypass control line and.said' abrasive supply line.

8. The device of claim 7 wherein said feed outlet is 1 providedlwith anorifice to meter a predetermined amount of abrasiveinto the air streamleadingto sa-id jet means and treating head.

9.. An apparatus for treating a surface with an' airconnecting saidapparatus to a sourceof compressed air,

anejector pump connected to a branch conduit of said air supply line tocreate a suction circuit, a-jet assembly connected to anotherbranchconduit of said airsupply line to create an air-blasting circuit,a treating head coupled with said jet assembly to utilize said airblast, said head including an air-pervious surface-contacting means toconfine the movement of loose material to an area within the head, asource of abrasive, a supply line from said abrasive source to said jetmeans, said jet means creating a vacuum in said supply line to inducethe flow of abrasive into the air blast in said head, an exhaustconnection between said suction circuit and said head, separating andreclaiming means for said abrasive interposed in said suction circuit, abypass suction line leading from said suction circuit to a connectionwith both said supply line and said abrasive source, and valve meansregulating the flow of blasting air to said jet assembly, whereby duringa blasting stage of operation abrasive material is sucked through thesupply line, blasted at the surface, removed through said suctioncircuit and reclaimed in said separating and reclaiming means, whereason closing said valve means said bypass line redirects the flow ofabrasive away from the treating head into an abrasive recycling stage ofoperation through said operating and reclaiming means, therebypermitting instantaneous stopping of the abrading action upon valveclosure.

10. An apparatus for treating a surface with an airblasted,suction-removed abrasive and for substantially eliminating time lag inthe operation of the apparatus, which comprises'an air supply line forconnecting said apparatus to a source of compressed air; an ejector pumpconnected to a branch conduit of said air supply line to create asuction circuit; a jet assembly connected to another branch conduit ofsaid air supply line to create an air-blasting circuit; valve meansregulating the flow of blasting air to said jet assembly; a treat-inghead coupled with said jet assembly to utilize said air blast, said headincluding an air-pervious surface-contacting means to confine themovement of loose material to an area within the head; a source ofabrasive; a supply line from said abrasive source to said jet means,said jet means creatinga reduced pressure in the outlet end of saidsupply line to induce the flow of abrasive into the air blast in saidhead; an exhaust line connecting said suction circuit to said head;separating and reclaiming means for said abrasive interposed in saidsuction circuit; a bypass line leading from said suction circuit to aconnection with both said supply line and said abrasive source, thepressure at the outlet end of said bypass line being higher than thepressure at the outlet end of said supply line during blasting and beingreversed when said jet means is inactivated by closing said valve means;whereby during blasting abrasive material is moved through said supplyline, is impelled at the surface being treated, is removed through saidsuction circuit and reclaimed in said separating and reclaiming means,and upon closing of said valve means and flow of abrasive in said supplyline is reversed thereby effecting an instantaneous stopping of theabrading action, and thereafter the abrasive cycles from the abrasivesource through said bypass line into said operating and reclaiming meansand back to said abrasive source until said valve means is again openedto resume blasting.

11. In a devicefor treating a surface with an airblasted, vacuum-removedabrasive having air compressor means for impell ing said abrasive at thesurface being treated, vacuum means for conveying the spent abrasiveaway from said surface, and suction control \means for eliminating timelag in the operation of the device; the combination of a treating headspaced slightly above and having an air-pervious maze adapted to coverover a portion of the surface being treated, said treating head havingan open end, a jet means therein with its open end pointed toward theopen end of said head and with its other end connected to said aircompressor and to a supply line in communication with a source ofabrasive, a vacuum conduit from said head to said vacuum means, asuction control line leading from a source of reduced pressure directlyto both said supply line and said source of abrasive, and a controlvalve interrupting the flow of air from said air compressor to said jetmeans, whereby on closing said valve during normal operation of thedevice, a flow of abrasive through said supply line into said treatinghead will be instantaneously redirected through said suction controlline.

12. An apparatus for achieving instant control over the abrading actioninvolved in treatment of a surface by impinging loose solid abrasivematerial against the surface which comprises a source of abrasivematerial, an air jet creating a source of reduced pressure in anabrasive supply line leading from said material source, thereby inducingflow of the material to the surface, an independent source of reducedpressure operable in a pickup line adjacent the surface to induce fiowaway from the surface of both said material and of solid particlesremoved from the surface, and a bypass line con meeting said independentsource of reduced pressure to said material source and said abrasivesupply line, whereby on closing of the air jet, said independent sourceof reduced pressure will operate through said bypass line toinstantaneously redirect the flow of abrasive material away from saidjet.

13. A surface-treating device, including in combination: a supply sourcefor treating material; a blasting gun for directing said material atsaid surface; a first conduit connecting said supply source to said gun;gunactuating means for producing simultaneously a first suction force insaid first conduit for causing said material to flow from said source tosaid gun, and an impelling force in said gun for projecting saidmaterial at said surface; control means for alternately rendering saidgun actuating means operative and inoperative; a second conduitconnected to said first conduit between said supply source and said gun;and means for producing a second suction force on said second conduit oflower magnitude than said first suction force and therefore not able tointerfere with the movement of material from said supply source to saidgun while said gunactuating means is operative, but, when saidgun-actuating means is inoperative, serving immediately to redirect saidmaterial away from said gun and through said second conduit so that thensaid material never reaches said gun.

14. In an apparatus for treating a surface with a loose abrasivematerial, for providing instantaneous stop-andstart control over thetreating action, and for collecting and preventing loose material fromsuch treatment from flying about, said apparatus having a casing with anopen end; suction means connected to said casing; jet means within saidcasing for projecting said material at said surface through said openend; air-permeable, mazelike impeding means projecting from said end andimpeding the exit of said material while said suction means draws in airthrough said maze-like means and carries away said material; a source ofsaid treating material; and a supply conduit connecting said source tosaid jet means; the combination therewith of: a bypass control conduitconnecting said supply conduit to said suction means; means at said jetmeans for producing a suction force on said supply conduit greater thanthat produced thereon by said bypass control conduit; and means forrendering said jet means alternately effective and ineffective, wherebywhen said jet means is effective it immediately draws material from saidsupply source and projects it through said gun and when said jet meansis ineffective said suction immediately acts through said bypass controlconduit to reverse the flow of said material and move it away from saidgun through said bypass control conduit.

15. In an apparatus for treating a surface and having a casing with anopen end spaced slightly above said surface, air pervious deflectormeans secured around said open end and adapted to rest on said surfaceand surround the space between said open end and said surface, andsuction means connected to said casing, the combina- ;tion therewith,for the purpose of substantially eliminating time lag in the operationthereof, of: a source of treating material; a supply line connectingsaid source of treating material to said casing; a control lineconnecting said supply line to said source of suction and bypassing saidcasing; jet means projecting within said casing and forming theconnection of said supply line to said casing; means for supplying airunder pressure to said jet means; and valve means regulating the supplyof said air to said jet means, said valve in open position creating aforce of suction on said supply line greater than that in said controlline so that treating material passes through said supply line to saidjet means and is projected thereby against said surface, whence it iswithdrawn by said suction means without passing outward through saiddeflector means, whereas said valve in closed position re sults in saidtreated material reversing its flow to said jet means and flowing awaytherefrom through said control line.

16. A device for achieving instantaneous control over the stopping andstarting of abrading action involved in surface-treating operations ofthe type where loose, solid abrasive is impinged against a surface, saiddevice including in combination: a treating head; a source of abrasive;an air jet connected to said head and creating a reduced pressure withina portion of said jet; a supply line from said source to said jet, saidreduced pressure inducing flow of abrasive therethrough; a second sourceof reduced pressure connected to said supply line and exerting a lesserforce than that of said jet upon said supply line and said source ofabrasive; an air source supplying said air jet; and a valve forinterrupting the flow of air from said air source to said jet, whereuponsaid source of reduced pressure immediately reduces the flow of abrasiveaway from said head.

17. The device of claim 16 in which said air jet includes a nozzle incommunication with said source of abrasive and a mixing tube spacedabout said nozzle to produce an orifice gap between the two, said nozzlebeing axially adjustable with respect to said nozzle to vary thedimensions of said orifice gap, whereby abrasive materials of varyingquantities may be impelled at the surface.

18. A device for achieving instantaneous control over the stopping of asurface abrading action produced through the impingement of granularabrasive against a work surface, including in combination: a source ofabrasive; first suction means for moving said abrasive material fromsaid source and toward and against said work surface; a second smallersuction means opposing said first means; and means for instantaneouslystopping said first means so that said second means reverses the flow ofabrasive material and instantaneously stops the abrading action againstthe work surface by redirecting said abrasive.

References Cited in the file of this patent UNITED STATES PATENTS2,365,250 Crowley Dec. 19, 1944 2,455,514 Mead Dec. 7, 1948 2,483,176Bishop Sept. 27, 1949 2,494,773 Mead Jan. 17, 1950 2,503,743 Keefer Apr.11, 1950 2,521,931 Mead Sept. 12, 1950 2,597,434 Bishop May 20, 1952FOREIGN PATENTS 614,087 France Sept. 11, 1926

